Currently, 12V starter motors and enhanced 12V starter motors are the most cost effective engine cranking devices. An enhanced starter motor has the capability to deliver circa 300,000 starts during a 150,000 mile 10-year vehicle lifetime. The ring gear with which the starter motor engages has the capability to deliver circa 400,000 starts over the same 150,000 mile 10-year vehicle lifetime.
In modern micro hybrid, mild hybrid, full hybrid or plug-in hybrid vehicles, engine stop-starts are required when the vehicle is stationary as well as when the vehicle is rolling. The required number of engine starts during a typical 150,000 mile 10-year vehicle life is greater than either an enhanced starter motor or a wear optimized ring gear are able to provide and cost effective alternatives are not available. Therefore, it may be difficult for an engine starting system to achieve a desired number of engine starts over a prescribed duration.
It is an object of the present description to provide a method of starting an engine and an apparatus for starting an engine that provide an increased service life in an economical manner.
The inventors herein have recognized the above-mentioned challenges and have developed a method for starting an engine having a starting apparatus including at least two starter motors wherein the method comprises sharing starting of the engine between the starter motors to equalize the wear of the starter motors and reduce the number of engine starts performed by each starter motor. The number of starts performed by each starter motor may be equal to the total number of engine starts performed divided by the total number of active starter motors. The number of starts performed by each starter motor may be equal to the total number of engine starts performed in a period of time divided by the total number of active starter motors in the period of time.
In one example, no active starter motor may be used for two consecutive engine starts. Further, each starter motor may be engageable with a ring gear to start the engine and may produce a respective wear pattern on the ring gear and the starter motors may be positioned so as to minimize overlap between the respective wear patterns produced by the starter motors. There may be first and second starter motors and the two starter motors may be used in an alternating sequence. The method may further comprise checking to see whether the engine has started following the use of a respective starter motor and, if the engine has not been started by the respective starter motor using another starter motor to start the engine and deactivating the respective degraded starter motor. The method may further comprise providing a warning to a user of the engine that the respective starter motor has become degraded. The method may further comprise providing a warning to a user of the engine of a total system degradation condition if all of the starter motors have not started the engine.
By selecting which of two starters is to start an engine, it may be possible to extend an amount of time for starter degradation. For example, it may be possible to double a time interval or a number of engine restarts between starter degradation. As a result, a vehicle that is automatically stopped and restarted may be serviced for a degraded starter at nearly the same time or number of engine starts as an engine that is not automatically stopped and restarted.
According to a second aspect of the description there is provided an apparatus for starting an internal combustion engine having a flywheel connected to a crankshaft of the engine wherein the apparatus comprises a starter ring gear fastened to the flywheel, at least two starter motors each having a pinion wheel for selective engagement with the ring gear and an electronic controller to control the operation of the starter motors wherein the electronic controller is operable to use the starter motors in a predefined sequence to equalize wear of the starter motors and reduce the number of starts performed by each starter motor.
The electronic controller may operate the starter motors so that the number of starts performed by each starter motor is equal to the total number of engine starts performed divided by the total number of active starter motors. In one example, no active starter motor may be used for two consecutive engine starts. Further, each starter motor may be engageable with the ring gear to start the engine and may produce a respective wear pattern on the ring gear and the starter motors may be positioned so as to minimize overlap between the respective wear patterns produced by the starter motors. Additionally, there may be first and second starter motors and the two starter motors may be used in an alternating sequence.
The engine may be a four cylinder, four stroke engine and the second starter motor may be positioned relative to the position of the first starter motor at an angle in the range of 60 to 120 degrees measured in the direction of rotation of the ring gear so as to minimize overlap between the respective wear patterns produced by the two starter motors. The engine may be a four cylinder, four stroke engine and the second starter motor may be positioned relative to the position of the first starter motor at an angle in a range of 240 to 300 degrees measured in the direction of rotation of the ring gear so as to minimize overlap between the respective wear patterns produced by the two starter motors.
The apparatus may comprise two starter ring gears fastened to the flywheel and at least two starter motors associated with each ring gear, each starter motor having a pinion wheel for selective engagement with the respective ring gear and the electronic controller may control the operation of the starter motors to equalize wear of the starter motors and reduce the number of engine starts performed by each starter motor.
The electronic controller may be further operable to check whether the engine has started following the use of a respective starter motor and, if the engine has not been started by the respective starter motor, uses another starter motor to start the engine and deactivates the respective failed starter motor. The electronic controller may be further operable to provide a warning to a user of the engine that the respective starter motor has failed.
According to a third aspect of the description there is provided a motor vehicle having an apparatus constructed in accordance with said second aspect of the description.
According to a fourth aspect of the description there is provided a method for increasing the life of a starter ring gear comprising using a first starter motor in a first position for a predefined number of engine starts and then replacing the starter motor with a replacement starter motor positioned so as to produce a wear pattern having minimal overlap with a wear pattern produced by the first starter motor.
The method may further comprise using a first pair of starter motors in respective first positions for a predefined number of engine starts and then replacing the first pair of starter motors with a replacement pair of starter motors positioned so as to produce wear patterns having minimal overlap with wear patterns produced by the first pair of starter motors.
The present description may provide several advantages. In particular, the approach may extend a time between starter service intervals. Further, the approach may improve vehicle durability. Further still, the approach may reduce driveline wear, thereby increasing the operating life of the driveline.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.